The present invention relates to new organic compounds and liquid crystal compositions containing the compounds, and more particularly, the present invention relates to optically active compounds having an optically active group, liquid crystal compositions containing the compounds and electro optical elements using the compositions.
Liquid crystal display elements are widely used as various display elements, such was watches, electronic calculators, television sets, computer ends, etc., because these elements have excellent characteristics, such as operatively at low voltage, minimized consumption of electric power, obtainability of thin display elements and so on.
At present, display elements of a twisted nematic (TN) type are widely used as liquid crystal display elements. However, the response of the display element is slower than that of a display element of light emitting type such as an electroluminescence display, a plasma display, and the like. Although improvement of the response time of the liquid crystal display has been tried in many ways, it shows no sign of marked improvement.
However, a new display method using a ferroelectric liquid crystal that has been studied has hope for the improvement of the response time. (Clark et al., Appl. Phys. Lett., 36, 899(1980)). This display method utilizes a ferroelectric chiral smectic C phase (abbreviated as S.sub.c.sup.* phase hereinafter) or other smectic phase such as a chiral smectic F, G, H or I phase, and the like. This method has a quick response time less than 1/100 to 1/1000 of that of the TN display method and a memory effect of bistability. It is expected to have wide application of a large sized television set of dynamic picture display, a high-speed light shutter, and the like.
However, in spite of these excellent characteristics, already-known compounds do not show a very quick response The reason is that a compound having a high value of spontaneous polarization in the ferroelectric liquid crystal phase is unknown. The spontaneous polarization value is proportional to the response rate. It is known that the high value of spontaneous polarization is important to obtain the quick response, but compounds having the high value of spontaneous polarization were not found.
An object of the present invention is to provide optically active compounds having characteristics suited for the display method which is still being researched, especially having enough spontaneous polarization to realize a quick response.